Floor grinding machine



Feb. 24, 1970 F. A. OSWALD FLOOR GRINDING MACHINE 3 Sheets-Sheet 1 Filed Nov. 16, 1965 INVENTOR.

FRED A. OSWALD W -mzw Feb. 24, 1970 'F.- A. O'sWALD 3,496,631

7 FLOOR GRINDING momma Filed Nov. 16. 1965 s Sheets-Sheet 2 E INVENTOR.

. EFF/2E0 A. OSWALD 73 f WBW is 3 Sheets-Sheet 5 I INVENTOR FRED- ,A. OSWALD 1-". A.- OSWALD FLOOR GRINDING MACHINE Feb. 24, 1970 Filed Nov. 16. 1965 United States Patent 3,496,681 FLOOR GRINDING MACHINE Fred A. Oswald, 5017 47th Ave., Woodside, N.Y. 11377 Filed Nov. 16, 1965, Ser. No. 508,079 Int. Cl. B24b 23/00; A471 11/00 us. Cl. 51-177 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a floor grinding machine. The invention more particularly relates to an improved floor grinding machine for grinding terrazzo fioors.

Terrazzo floors are initially formed from poured concrete containing small marble chips. After the pouring and setting the floor surface must first be rough ground and then polished in order to render the same flat and smooth and to give the characteristic terrazzo appearance.

The rough grinding is generally a tedious time consuming and thus costly operation which involves the wheeling of a grinding machine back and forth along the floor. The most common prior art grinding machines utilize rotating grinding disks having abrasive blocks of aluminum oxide or similar abrasives which are moved in grinding contact with the floor. The grinding operation is generally effected as a wet grinding and water was fed between the blocks and the floor during the operation. Only a relatively small amount of material could be removed by the grinding at each pass and the abrasive blocks would wear quickly requiring frequent changes.

Terrazzo floor grinding machines utilizing diamond containing abrasive blocks have also been proposed. These machines grind at a faster rate and the abrasive blocks are much longer wearing. Due to the higher cutting rate however the maintaining of a uniform grinding pressure is more critical to successful operation and it is highly desirable that the operator be able to initially adjust the grinding pressure depending on the floor condition and to be able quickly to remove the blocks from grinding engagement and return the same with the same grinding pressure.

One object of this invention is a floor grinding machine for terrazzo floors capable of being operated in the above described manner.

A further object of this invention is a high speed terrazzo floor grinding machine in which the abrasive blocks may be maintained in very accurate grinding position at a preadjusted pressure and in connection with which the same may be quickly lifted out of grinding engagement and quickly returned at the preadjusted pressure.

A further object of this invention is a terrazzo floor grinding machine which utilizes diamond containing grinding abrasive and which may be operated more accurately and at a higher grinding rate than the prior art machines.

These still further objects will become apparent from the following description read in conjunction with the drawings in which:

FIG. 1 is a perspective view of an embodiment of a machine in accordance with the invention.

FIG. 2 is a further perspective view of the machine shown in FIG. 1.

FIG. 3 is diagrammatic side elevation showing the adjustment controls of the machine in FIG. 1.

3,496,681 Patented Feb. 24, 1970 FIG. 4 is a vertical cross section of the grinding head and shaft of the embodiment of FIG. 1.

FIG. 5 is a bottom plan view of the machine of FIG. 1, and

FIG. 6 is a top plan view of the machine of FIG. 1.

The floor grinding machine in accordance with the invention has a wheeled carriage adapted to be rolled across a floor to be ground. Preferably this carriage has front and rear wheels and most preferaby a pair of fixed front wheels and one or more pivotable tail wheels. A vertical rotary drive shaft is mounted on the carriage for limited axial movement and is adjustably urged downwardly with a resilient force. Grinding means such as a grinding disk with diamond containing abrasive blocks are mounted at the end of the shaft for grinding engagement with the floor as the carriage is wheeled along. Drive means are provided for rotating the shaft and means are provided for raising the grinding means out of grinding engagement. Preferably the grinding means are moved out of grinding engagement by providing means for raising and lowering the carriage with respect to its wheels between a lowered grinding position and a raised nongrinding position.

Referring to the embodiment shown in the drawing, 1 designates a carriage which is adapted to be rolled along a floor to be ground on the axially spaced apart front wheels 2 and the pivotable rear or tail wheel 3. The carriage is provided with the handle arrangement 4 in order to allow the operator to push and manipulate the same. A hand lever 5 is pivotably connected to the carriage at 6 and a connecting rod 7 connects the lever 5 to a cross bar 8 which in turn is connected to a pair of spaced apart bell crank levers 9. Each of the front wheels 2 is connected to the other end of an individual bell crank lever 9, the center of the bell crank levers being pivotably connected to the carriage at 10. When the lever 5 is released in the position shown in FIG. 3 the carriage 1 is lowered with respect to the front wheels 2 so that the machine will be in its grinding or operable position as hereinafter described. When the lever 5 is pulled backwardly as shown in FIG. 1 the bell crank lever 9 is rotated and the carriage 1 is thus raised with respect to the wheels 2 so that the machine will be raised to a non-grinding position as hereinafter described. The lever 5 may be retained in its rear position by means of the hook 11 and eye 12, the hook 11 being attached to the handles 4 and the eye 12 to the lever 5. Mounted on the carriage in front of the front wheels are a pair of vertical side by side tubular shaft casings 13. Within each of the tubular shaft casings as may best be seen from FIG. 4 is the tubular bearing support sleeve 14 which carries the roller bearings 15 and 16. The sleeve 14 is slidably mounted in the casing 13 having the slide ring 17 connected thereto which slides along the inner surface of the sleeve 13. A similar slide ring 17A aligns sleeve 14 axially inside sleeve 13 and the sleeve and casing 14 and 13 slide in contact therewith. Adjustment posts 18 connect the slide ring 17A to the upper adjustment flange 19 and a coil spring 20 is compressed between the rings 17A and 17. Rotatably mounted in the bearings 15 and 16 is the drive shaft 21. Connected to the lower end of the drive shaft 21 by a flexible connection in the form of the universal joint 22 is the grinding disk 23 having the diamond containing abrasive segments 24, as may best be seen from FIG. 5

The universal joint designated at 22 is formed with the upper disk which is rigidly connected to the shaft 21 and two diametrically opposed pillar blocks 26 which are secured to this upper disk 25 by welding. A cross rod 27 pivots in these pillar blocks 26. Further pillar blocks 28 are secured to the disk 23 by welding and the other arms of the cross bar 27 extend through these 3 pillar blocks 28 which allow pivoting of the disk 23 with respect thereto.

A pulley shaft 29 is rotatably mounted above the casing 13 in the bearings 30 and 31. The pulley shaft 29" is connected for rotation with the drive shaft 21 by means of the sliding splined joint 32. A drive pulley 33 is connected to the upper end of the pulley shaft 29. Both the pulley shaft 29 and the drive shaft 21 are hollow and a water pipe 34 extends through the hollow interior thereof. This water pipe terminates at the lower with an outlet nozzle 35 which is directed through a hole 36 in the upper disk 25 and a hole 37 in the disk 23 so that Water may be directed through the pipe 34 onto the floor for the grinding operation. The pipes 34 are cross connected by the cross pipe 38 which is fed through the T connection 39 by the flexible water hose 40 connected to a water supply. Pivotably mounted on the upper end of the upright support post 41 connected to the carriage is the cross bar 42. Rigidly connected at each end of this cross bar 42 is a lever arm 43 with a wheel 44. One of the wheels 44 rests in engagement with the flange plate 19 of one of the shaft casing units and the other wheel 44 is in contact with the flange 19 of the other shaft casing unit. Rigidly connected to the central portion of the cross bar 44 is the lever plate 45 provided with a central threaded opening through which the threaded end 46 of the crank column 47 extends. The opposite end of the column 47 is provided with the crank wheel and handle 48. Column 47 extends through a bearing 49 connected to the handle 4 which allows rotation of the column 47 without axial movement. Thus by cranking the crank wheel 48 the plate 45 is screwed along threaded portion 46 pivoting the bar 42 and actuating the lever arms 43 and wheels 44 in the manner of a bell crank lever. Depending on the direction of rotation of the crank 48 the flanges 19 are moved up or down, thus decreasing or increasing the pressure of the springs 20 by action of the posts 18 on the rings 17A. By cranking the handle 48 so that the plate 45 moves toward the screw end of the column 47 the spring pressure is increased and in the reverse direction the spring pressure is decreased. With an increase in the spring pressure, the tubular bearings sleeve 14 for bearings 15 and 16 and the drive shaft 21 is forced down with a greater pressure thus exerting a greater grinding pressure between diamond abrasive blocks 24 and the floor. Conversely by reducing spring pressure the grinding pressure is decreased.

Mounted on the carriage 1 between the front and rear wheels are a pair of electric motors 50 and 51 as for example 7 /2 H.P. motors. These motors are vertically mounted with the drive shafts extending upwardly. There attached to the upper end of each of these electric motors is a drive pulley 52 and 53 respectively. The drive pulley 52 is connected by means of the drive belt 52a to the pulley 33 of the shaft casing unit immediately in front of it and the pulley 53 is connected in the same manner by a belt 53a to the pulley 33 of the shaft casing unit immediately in front of it. The pulleys and belt arrangements may be provided with protective covers or casings as shown in FIG. 2. The motors 50 and 51 are connected by a conventional power cord to an electrical supply through the control boxes 54 and 55 respectively provided with the on and off switches. A box 56 with an ammeter for each motor may be provided for determining overload conditions. I

In operation if the hand lever is pulled rearwardly and secured in this position by means of the hooks 11 and the eye 12 the bell crank levers 9 are pivoted so that the wheels 2 are extended with respect to the carriage and the carriage is raised so that the diamond abrasive blocks 24 are clear of the floor and the device may be freely wheeled across the floor or transported in this manner without interference. For operation the motors are started driving the disks 23 in opposite directions at for example 2,000 rpm. and water from an ordinary garden hose type connection is passed through the pipe 40 passing through the pipes 34 and out through the the outlet nozzles 35 and the holes 36 and 37 wetting the floor in the area of the diamond abrasive blocks 24. By releasing the hook 11 and slowly allowing the lever 5 to move forward the carriage 1 is lowered due to the retraction of the front wheels 2 with respect thereto so that the abrasive blocks 24 come into grinding engagement with the floor. The grinding pressure may be very accurately adjusted by means of the crank handle 48. The carriage is wheeled back and forth across the floor for the grinding operation and may be very readily maneuvered due to the pivotable tail wheel 3. As the carriage is stabilized between the front and rear wheels pressure pulling or pushing the handle 4 does not vary the grinding pressure which is simply controlled by adjustment of the crank wheel 48. The combination of the axially movable spring loaded drive shaft 21 and the flexible connection of the disk 23 to the shaft provides the uniform floating grinding action which may be very accurately controlled. The abrasive blocks 24 may be quickly and easily raised out of grinding engagement with the floor by the operator simply pulling back on the lever 5 and may be returned to grinding engagement by allowing the lever 5 to go forward again, in each case being returned to the exact preset grinding pressure as determined by the adjustment of the crank wheel 48. Though this pressure adjustment simultaneously effects both grinding shafts, each shaft can independently compensate for unevenness in the floor due to its individual spring loading.

While the invention has been described in detail with reference to the specific embodiments shown, various changes and modifications which fall within the spirit of the invention and scope of the appended claims will become apparent to the skilled artisan. The invention is, therefore, only intended to be limited by the appended claims or their equivalents wherein I have endeavored to claim all inherent novelty.

I claim:

1. Floor grinding means comprising a wheeled carriage adapted to be rolled along a floor to be ground, a vertical rotatable drive shaft mounted on said carriage for limited axial movement, means axially urging said shaft downwardly with a resilient force, said means for axially urging said shaft downwardly comprising an axially slidable bearing sleeve having bearings secured thereto in which said drive shaft is rotatably mounted, a resilient mechanism urging said sleeve downwardly, means for etxernally adjusting said resilient mechanism, 'a universal joint, grinding means mounted by said universal joint at the end of said shaft for grinding engagement with a floor, means for rotating said shaft and means for raising said grinding means to a position out of said grinding engagement.

2. Floor grinding machine comprising a wheel carriage adapted to be rolled along a floor to be ground, a vertical rotary drive shaft mounted on said carriage for limited axial movement, means axially urging said shaft downwardly with a resilient force, means for externally adjusting said resilient force, grinding means mounted at the end of said shaft for grinding engagement with a floor, means for rotating said shaft, means for raising said grinding means to a position out of said grinding engagement, front and rear wheels rotatably mounted on said carriage for movement of said carriage along a floor to be ground, a lever arrangement for raising and lowering said carriage with respect to said front wheels between a lower grinding position and a raised nongrinding position, a pair of vertical shaft castings mounted side by side on said carriage forward of said front wheels, a shaft bearing arrangement axially slidably positioned in each said shaft casing, spring means biasing each said shaft bearing arrangement downwardly, external adjusting means mounted on said carriage for varying the spring force, a vertical rotary drive shaft rotatably mounted in each bearing arrangement, a grinding disk with diamond abrasive flexibly mounted on the end of each shaft in grinding arrangement with a floor when said carriage is in its lowered position, a pair of drive motors mounted side by side on said carriage between the said front and rear wheels, transmission means including a belt drive connecting each motor to a separate drive shaft for rotating said drive shafts in opposite directions, and means for feeding water under said disks.

3. Floor grinding machine according to claim 2 including water conduits extending through said drive shafts for feeding water.

4. Floor grinding machine according to claim 2 in which said discs are mounted on the end of said shafts by universal joints.

5. Floor grinding machine according to claim 4 in which said shafts are rotatably mounted in tubular bearing sleeves slidably mounted in said shaft casings and including a coil spring positioned between each said shaft casing and said tubular bearing sleeve slidably urging said tubular bearing casings downwardlys, a flange positioned above each of said shaft casings and connected for pressure actuation on the upper end of the coil spring associated with that shaft casing, a bell crank lever arrangement for pressure actuation on each said flange and a crank handle arrangement for actuation of said bell crank lever.

6. Floors grinding machine according to claim 2 in which said front wheels are pivotably mounted on a bell crank lever and in which said lever arrangement for raising and lowering said front wheels includes a hand lever pivotably mounted on said carriage and connected to said bell crank lever through a connecting rod.

7. Floor grinding machine according to claim 2 in which said rear wheel is a single pivotably mounted tail wheel.

References Cited UNITED STATES PATENTS 1,663,759 3/1928 Ham. 1,571,571 2/1926 Cavicchi 5l177 1,583,145 5/1926 Haynes 51177 1,601,087 9/1926 Simpson 15-49 1,773,992 8/1930 Gillis 15-49 1,924,582 8/1933 Wineman 51-177 OTHELL M. SIMPSON, Primary Examiner U5 X-R, 49 

